MS/TP Frame Format Error

The MS/TP frame does not conform to the expected format: preamble, destination address, length, control, or CRC. Receiving node discards the frame. Often indicates physical layer or timing problems.

Common Causes

Electrical noise corrupting frame bytes (similar to CRC error)
Baud rate mismatch between nodes (e.g., 76.8k vs 38.4k)
Voltage drop or marginal signal causing bit errors
Faulty transceiver or damaged cable introducing garbage

Fix Steps

Verify all nodes use the same baud rate (76.8 kbps typical for MS/TP).
Check RS-485 differential voltage and wiring; fix voltage drop or noise.
Ensure proper termination and no ground loops affecting signal integrity.
Inspect transceivers and cabling for damage; replace suspect components.
Use protocol analyzer to capture raw frames if errors persist.